Attrition resistant metal/oxygen compositions and a process for their preparation

ABSTRACT

Attrition resistant metal/oxygen compositions comprising the infusion and reaction product of alumina and at least one metal oxide, or compound convertible by heat to such metal oxide, which metal oxide is susceptible of undergoing infusion and reaction with the alumina, are useful in a wide variety of metal oxide-catalyzed reactions. The compositions are especially useful in reactions which involve reaction conditions of high stress, for example, vapor phase oxidations under fluidized bed conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

"Attrition Resistant Metal/Oxygen Compositions," Ser. No. 335,791 and335,792 and "Attrition Resistant Bismuth-Containing Metal/OxygenCompositions," Ser. No. 335,786, all filed Dec. 30, 1981.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to attrition resistant metal/oxygen compositionsand a process for preparing such compositions. More particularly, thisinvention relates to metal/oxygen compositions comprising the infusionand reaction product of:

(a) an alumina existing in a crystal form selected from the groupconsisting of γ, δ, η, and χ crystal forms, and mixtures thereof, orthat can be transformed by heat to such crystal forms, and characterizedby

(i) a mean particle size from about 10 μm to about 200 μm,

(ii) a fractional porosity of at least 0.2,

(iii) a surface area of at least 150 m² /g, and

(iv) a pore diameter such that at least 10 percent of the pores are lessthan 55 A, and

(b) at least one metal oxide, or compound convertible by heat to suchmetal oxide, having a maximum mean particle size of about 100 μm, withthe proviso that the alumina/metal oxide mean particle size ratio is atleast 2, which metal oxide is susceptible of undergoing infusion andreaction with the alumina upon being subjected to temperatures of atleast 0.4 T_(m) for a time sufficient to cause infusion and reactionbetween the metal oxide and the alumina, wherein T_(m) is the meltingpoint in °K. of the alumina.

The attrition resistant metal/oxygen compositions of this invention maybe used for any of a wide variety of purposes generally known in theart. Thus, for example, the compositions are useful in thetransformation of numerous organic compounds in the vapor phase such asdehydrogenation reactions, oxidation reactions, hydrogenation reactions,isomerization reactions, dealkylation reactions, dehydrocouplingreactions, and the like. The compositions may be employed in a manneridentical to that for metal/oxygen compositions heretofore known in theart for such transformations.

2. Description of the Prior Art

Supported metal oxides are well-known as catalysts and oxygen carriersfor a wide variety of chemical reactions. In general, such metal oxidecompositions are comprised of a metal oxide coated on a support materialof low porosity and low surface area. Such support is commonly referredto as an inert support. The method generally employed to produce thesesupported metal oxide compositions involves impregnating the inertsupport with a solution of a soluble salt of the metal oxide, separatingthe resultant impregnated solid, and heating to remove a substantialportion of the solvent. The impregnated solid is then calcined atelevated temperatures to convert the metal salt to the correspondingmetal oxide. Multiple impregnations are sometimes employed to achieve anincreased concentration of metal oxide on the support.

Another well-known technique employed for forming supported metal oxidecompositions involves suspending the support materials in a solution ofa salt of the metal, completely or partially evaporating the solvent,and possibly mixing the resultant material with an organic binder andpelletizing thereof. The dry pellet is then heated to an elevatedtemperature to effect complete dehydration and burning out of theorganic material.

A method for forming a supported metal oxide on a porous support isdisclosed in U.S. Pat. No. 3,925,447 which involves contacting theporous support material with the metal oxide in molten form to produce acatalyst in which the metal oxide is substantially entirely within thepores of the support. The resultant catalyst is used in the productionof nitriles.

U.S. Pat. No. 3,668,151 discloses a high strength (as indicated by itscrush strength) zinc aluminate catalyst composition. Upon beingimpregnated with platinum, lithium, and tin in the usual manner, theresultant catalyst was used to dehydrogenate n-butane to olefins anddiolefins, presumably 1- and 2-butene and 1,3-butadiene.

A substantially identical zinc aluminate catalyst having an approximatemole ratio of zinc oxide to alumina of 1 also is disclosed in U.S. Pat.No. 4,260,845. The catalyst is reported to be useful for dehydration ofsaturated alcohols to olefins, for example, 2-methyl-1-butanol to2-methyl-1-butene.

Although these prior art compositions are generally suitable for theirstated purposes, the commercial utility of catalysts and oxygen carriercompositions in reactions which involve reaction conditions of highstress (such as high temperatures and/or pressures, especially underfluidized bed conditions) require compositions which are highlyresistant to abrasion and attrition due to the deleterious effects ofreaction conditions. Accordingly, research efforts are continually beingmade for high efficiency catalyst and oxygen carrier compositions ofincreased physical strength and attrition resistance which are useful inreactions involving conditions of high stress. The discovery of thecompositions of the present invention, therefore, is believed to be adecided advance in the catalyst and oxygen carrier composition art.

SUMMARY OF THE INVENTION

It is an object of this invention to provide attrition resistantmetal/oxygen compositions.

Another object of this invention is to provide attrition resistantmetal/oxygen compositions highly effective for the vapor phasetransformation of organic compounds.

Yet another object of this invention is to provide attrition resistantmetal/oxygen compositions highly effective as combinationcatalyst/oxygen carrier compositions in the vapor phase oxidativedehydrocoupling of toluene to yield toluene dehydrocoupled products inhigh yields and selectivities.

Still another object of this invention is to provide a process for thepreparation of attrition resistant metal/oxygen compositions effectivefor the vapor phase transformation of organic compounds.

To achieve these and other objects which will become apparent from theaccompanying description and claims, attrition resistant metal/oxygencompositions are provided which comprise the infusion and reactionproduct of:

(a) an alumina existing in a crystal form selected from the groupconsisting of γ, δ, η, and χ crystal forms, and mixtures thereof, orthat can be transformed by heat to such crystal forms, and characterizedby

(i) a mean particle size from about 10 μm to about 200 μm,

(ii) a fractional porosity of at least 0.2,

(iii) a surface area of at least 150 m² /g, and

(iv) a pore diameter such that at least 10 percent of the pores are lessthan 55 A, and

(b) at least one metal oxide, or compound convertible by heat to suchmetal oxide, having a maximum mean particle size of about 100 μm, withthe proviso that the alumina/metal oxide mean particle size ratio is atleast 2, which metal oxide is susceptible of undergoing infusion andreaction with the alumina upon being subjected to temperatures of atleast 0.4 T_(m) for a time sufficient to cause infusion and reactionbetween the metal oxide and the alumina, wherein T_(m) is the meltingpoint in °K. of the alumina.

The provision of the process for the preparation of such compositionsobject is achieved by a process which comprises:

(a) forming a mixture of an alumina existing in a crystal form selectedfrom the group consisting of γ, δ, η, and χ crystal forms, and mixturesthereof, or that can be transformed by heat to such crystal forms, andcharacterized by

(i) a mean particle size from about 10 μm to about 200 μm,

(ii) a fractional porosity of at least 0.2,

(iii) a surface area of at least 150 m² /g, and

(iv) a pore diameter such that at least 10 percent of the pores are lessthan 55 A, and at least one metal oxide, or compound convertible by heatto such metal oxide, having a maximum mean particle size of about 100μm, with the proviso that the alumina/metal oxide mean particle sizeratio is at least 2, which metal oxide is susceptible of undergoinginfusion and reaction with the alumina, and

(b) heating the mixture to a temperature of at least 0.4 T_(m) for atime sufficient to cause infusion and reaction between the metal oxideand the alumina, wherein T_(m) is the melting point in °K. of thealumina.

The provision of the toluene dehydrocoupling process object is achievedby a process which comprises:

(a) contacting the toluene in the vapor phase at a temperature fromabout 450° C. to about 650° C. with an attrition resistant metal/oxygencomposition comprising the infusion and reaction product of

(i) an alumina existing in a crystal form selected from the groupconsisting of γ, δ, η, and χ crystal forms, and mixtures thereof, orthat can be transformed by heat to such crystal forms, and characterizedby

(a) a mean particle size from about 10 μm to about 200 μm,

(b) a fractional porosity of at least 0.2,

(c) a surface area of at least 150 m² /g, and

(d) a pore diameter such that at least 10 percent of the pores are lessthan 55 A, and

(ii) at least one metal oxide, or compound convertible by heat to suchmetal oxide, having a maximum mean particle size of about 100 μm, withthe proviso that the alumina/metal oxide mean particle size ratio is atleast 2, which metal oxide is susceptible of undergoing infusion andreaction with the alumina upon being subjected to temperatures of atleast 0.4 T_(m) for a time sufficient to cause infusion and reactionbetween the metal oxide and the alumina, wherein T_(m) is the meltingpoint in °K. of the alumina, and

(b) recovering the toluene dehydrocoupled product.

Other objects and advantages of the present invention will becomeapparent from the accompanying description and claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. The Compositions

The attrition resistant metal/oxygen compositions of the presentinvention comprise the infusion and reaction product of:

(a) an alumina existing in a crystal form selected from the groupconsisting of γ, δ, η, and χ crystal forms, and mixtures thereof, orthat can be transformed by heat to such crystal forms, and characterizedby

(i) a mean particle size from about 10 μm to about 200 μm,

(ii) a fractional porosity of at least 0.2,

(iii) a surface area of at least 150 m² /g, and

(iv) a pore diameter such that at least 10 percent of the pores are lessthan 55 A, and a maximum mean particle size of about 100 μm, with theproviso that the alumina/metal oxide mean particle size ratio is atleast 2, which metal oxide is susceptible of undergoing infusion andreaction with the alumina upon being subjected to temperatures of atleast 0.4 T_(m) for a time sufficient to cause infusion and reactionbetween the metal oxide and the alumina, wherein T_(m) is the meltingpoint in °K. of the alumina.

The attrition resistant characteristics of the metal/oxygen compositionsof the present invention, preferably an attrition rate less than 0.5weight percent/hour (as measured by an accelerated attrition testdescribed below), make them excellent for use in reactions which involvereaction conditions of high stress, particularly in a fluidized bedsystem at elevated temperatures and/or pressures.

The term "infusion" and related terms are employed herein to mean aprocess by which two adjacent solids of differing compositionshomogenize by diffusion of one of such solids into the other, forexample, the diffusion of the metal oxide into the alumina.

The term "fractional porosity" is employed herein to mean the ratio ofvoid space or volume in a particle to the bulk or total volume of thatparticle.

The term "attrition," as employed herein, means the art of wearing orgrinding down by friction and breakage of the structures into dust andfines.

The term "attrition rate," as employed herein, means an acceleratedattrition rate and refers to the rate of attrition as determined by anaccelerated attrition test described in Example 44, below.

The materials suitable for use as components of the metal/oxygencompositions of this invention must, of necessity, possess thoseproperties and characteristics which will yield attrition resistantcompositions. In addition, the component materials advantageously shouldyield metal/oxygen compositions which are suitably for the vapor phasetransformation of organic compounds, especially the dehydrocoupling oftoluene, to yield the desired products in high yields and selectivities.Such materials are available commercially from numerous catalyst andmetal oxide suppliers.

Aluminas which are useful as components of the attrition resistantmetal/oxygen compositions are fairly wide in scope. Such aluminas,however, must possess certain characterizing properties to be suitablefor use in the present invention. Included among such properties are (a)a mean particle size from about 10 μm to about 200 μm, and preferablyfrom about 20 μm to about 125 μm; and (b) a fractional porosity of atleast 0.2, with values from about 0.2 to about 0.8 being preferred, asurface area of at least 150 m² /g, and a pore diameter such that atleast 10 percent, preferably 30 percent, of the pores are less than 55 A(5.5 mm). In order to facilitate ease of fluidization, the aluminaparticles preferably are spheroidal in shape.

Aluminas suitable for use in the present invention are those whichpossess the aforementioned characterizing properties and, in addition,exist predominantly in a crystal form selected from the group consistingof gamma (γ), delta (δ), eta (η), and chi (χ) crystal forms, andmixtures thereof, or that can be transformed by heat to these crystalforms. Included among the latter grouping are hydrated aluminas such asBoehmite, pseudo-Boehmite, Bayerite, and Gibbsite.

Metal oxides suitable for use within the scope of the present inventionare not narrowly critical. Each metal oxide must, of necessity, besusceptible of undergoing infusion and reaction with the alumina underconditions hereinafter described to yield the attrition resistantmetal/oxygen composition. In addition, the metal oxide must have amaximum mean particle size of about 100 μm, with the proviso that thealumina/metal oxide mean particle size ratio is at least 2, andpreferably 15 or more. The stated mean particle size ratio permits themetal oxide and the alumina to undergo the desired infusion and reactionwith little, if any, material change in the original particle size ofthe alumina. This phenomenon results in the high strength attritionresistant metal/oxygen compositions of this invention.

Suitable metal oxides are exemplified by oxides of lithium (Li₂ O),sodium (Na₂ O), potassium (K₂ O), rubidium (Rb₂ O), cesium (Cs₂ O) ofGroup 1a; beryllium (BeO), magnesium (MgO), calcium (CaO), strontium(SrO), barium (BaO) of Group 2a; scandium (Sc₂ O₃), and yttrium (Y₂ O₃)of Group 3b; zirconium (ZrO₂) of Group 4b; vanadium V (V₂ O₅) of Group5b; zinc (ZnO) and cadmium (CdO) of Group 2b; boron (B₂ O₃), gallium(Ga₂ O₃), indium (In₂ O₃), and thallium (Tl₂ O₃) of Group 3a; germaniumIV (GeO₂), tin IV (SnO₂), and lead II (PbO) of Group 4a; phosphorus,arsenic, antimony, and bismuth of Group 5a; lanthanides; actinides;Groups 1b, 6b, 7b, and 8 of the Periodic Table of the Elements, andmixtures thereof.

Of these metal oxides, the oxides of potassium, calcium, zirconium,iron, boron, lead, antimony, and bismuth, and mixtures thereof arepreferred, especially for toluene dehydrocoupling reactions.

It will be noted, however, that while metal oxides are preferred for usein the present invention, the direct charging of metal oxides asstarting materials is not necessary. Any compound of the desired metalsuch as salts, hydroxides, and the like, which are convertible by heatto the corresponding metal oxide, and as such, may be considered as aprecursor thereof, may be used to provide indirectly the metal oxide forpreparing the attrition resistant metal/oxygen compositions of thepresent invention. Typical metal salts include the water-solublenitrates, carbonates, and acetates.

The term "Periodic Table of the Elements" as employed herein refers tothe Periodic Table of the Elements published in CRC Handbook ofChemistry and Physics, 60th ed., Weast, Ed., CRC Press Inc., Boca Raton,Fla. 1979, Inside Front Cover.

The metal oxide component ranges in an amount from about 20 mole percentto about 65 mole percent, based on the total number of moles of metaloxide and alumina in the metal/oxygen composition, and preferably fromabout 30 mole percent to about 55 mole percent. The alumina componentmakes up the remaining portion of the metal/oxygen composition, which,in view of the stated mole percent of the metal oxide component, mustrange from about 35 mole percent to about 80 mole percent. Preferably,however, the alumina component constitutes from about 45 mole percent toabout 70 mole percent of the metal/oxygen composition.

Alumina concentrations greater and less than the stated 35 to 80 molepercent range, surprisingly, have been found to be detrimental.Compositions having alumina concentrations outside the stated range (35to 80 mole percent) exhibit a marked decrease in attrition resistanceor, stated differently, an increase in attrition rae. Lowered attritionresistance, of course, results in increased abrasion, breakage, anddusting of composition structures under high stress use conditions. Suchabrasion, breakage, and dusting can cause undesirable pressure drop,flow problems, filter clogging, loss of fluidizability, and the likeunder such conditions, especially during operations employing fluidizedbed reactor systems.

The attrition resistant metal/oxygen compositions can be prepared inseveral ways. The simplest method involves intimately mixing at leastone suitable metal oxide having a maximum mean particle size of about100 μm with the desired alumina having a mean particle size from about10 μm to about 200 μm such that the alumina/metal oxide mean particlesize ratio is at least 2, in an amount sufficient to constitute fromabout 20 mole percent to about 65 mole percent of the composition. Themetal oxide and alumina components may be dry mixed or mixed byslurrying in a suitable wetting agent (wet mixed), for example, water oran organic compound such as methanol, ethanol, and the like. When awetting agent is employed in the mixing step, it is removed by heatingthe slurried mixture at a temperature and for a time sufficient tosubstantially remove the excess wetting agent. In general, heating at atemperature of about 150° C. to about 250° C., usually about 200° C.,for about 1 hour to about 5 hours, usually 2 hours, is sufficient. Itwill be recognized, however, that the actual time and temperature willdepend upon the particular wetting agent employed, the quantity ofmaterial, and the like. The dry mixed material may also be subjected tosimilar temperatures in order to remove any physically bound water.Continued heating of the dry mixture (from either the wet-mixed ordry-mixed components) at temperatures from about 250° C. to about 500°C. for about 1 hour to about 5 hours serves to decompose any salts whichare present and remove other volatile components.

Upon completion of the drying and removal of any other volatilecomponents, the dry mixture of metal oxide and alumina is calcined at atemperature of at least 0.4 T_(m) for a time sufficient to cause themetal oxide and the alumina to infuse in accordance with diffusionalbehavior in metal oxides as described in Freer, Journal of MaterialScience, 15, 803-824 (1980) and undergo reaction to yield the attritionresistant metal/oxygen compositions of the present invention. Thecalcination may be carried out in an inert atmosphere such as nitrogen,helium, and the like, or in air. In many instances, it may be desirableto conduct the initial calcination under an inert atmosphere in order toprevent oxidation of the metal ion of the metal oxide to a higheroxidation state which may prevent or severely curtail the necessaryinfusion. This initial calcination is then followed by a finalcalcination in air to form the desired metal/oxygen composition.

As previously noted, the calcination is carried out by heating the drymixture of metal oxide and alumina to a temperature of at least 0.4T_(m). It will be recognized that the actual temperature employed willdepend primarily on the diffusional behavior of the metal oxide with theparticular alumina. In a similar manner, the actual time employed willdepend upon the component materials employed, as well as the calcinationtemperature. As an example, since alumina has a melting point of about2273° K. (2000° C.), temperatures typically from about 800° C. (0.47T_(m)) to about 1400° C. (0.74 T_(m)) and a time from about 1 hour toabout 15 hours are sufficient. Preferably, a temperature from about 900°C. to about 1100° C. and a time from about 8 hours to about 12 hours areemployed, most preferably, a temperature from about 1000° C. to about1050° C. and a time from about 10 hours to about 11 hours.

The calcination (and infusion) may be effected in any calcinationapparatus known to the art. Non-limiting examples include ovens ormuffle furnaces containing fixed beds or moving beds, rotary kilns, andthe like.

In an alternative method of preparation, a suitable precursor hydroxideor salt of the metal oxide component such as a nitrate, carbonate, oracetate is intimately mixed with the alumina and infused and calcined aspreviously described. Another method involves the impregnation of thealumina with an aqueous solution of one or more of the precursor salts.Preferably, a high concentration of metal salt is employed in order tominimize the need for subsequent evaporation of solvent. After theimpregnation, the resultant product is subjected to the infusion andcalcining process as previously described.

2. Characterization of the Compositions

The attrition resistant metal/oxygen compositions of this invention aresubstantially free of unreacted metal oxide and alumina as determined byx-ray diffraction (XRD). That is, the starting material components,under the heating and/or calcining conditions employed, have undergoneinfusion and reaction to an extent sufficient to preclude having thestarting material components remain in an unreacted state. As a result,the compositions of the present invention are not simply activematerials supported on a porous support material; they, instead, arenovel compositions comprising the infusion and reaction product of analumina and at least one metal oxide, all as previously defined.

The compositions of this invention exhibit excellent attritionresistance when compared to supported catalysts and compositions of theprior art. An attrition rate less than 0.5 weight percent/hour is, ingeneral, preferred. In addition, the compositions demonstrate highactivities, as well as high selectivities, in the many and variedtransformations of organic compounds. In a preferred use embodiment,compositions prepared from oxides of lead, antimony, or bismuth, andmixtures thereof, and the previously described alumina have been foundto be particularly efficacious as oxygen carriers and/or catalysts inthe dehydrocoupling of toluene to stilbene and/or bibenzyl. Overall, andin general, metal and metal ions employed as catalysts in known priorart processes may be employed in the metal/oxygen compositions of thisinvention in the same mode to effect similar reactions, but with theadded advantage of increased attrition resistance.

The attrition resistance, calculated as the attrition rate in units ofweight percent/hour is determined by an accelerated attrition test. Inthis test, which is described in detail in Example 44 below, the weightin grams of dust and fines generated via abrasion, friction, andbreakage under stated conditions for a specified period of time, usuallythe 5-21 hour period (16 hours) out of a total of 21 hours, from aspecified weight in grams of a sample of the bulk composition ismeasured. Using these values, the percent attrition during the specifiedperiod can be calculated as follows: ##EQU1##

The attrition rate is then calculated as follows: ##EQU2##

It will be apparent, of course, that all things being equal with respectto properties exhibited by the metal/oxygen compositions of thisinvention, the greater the attrition resistance (expressed as a smallernumerical attrition rate value in units of weight percent/hour), themore desirable such compositions become in that fewer difficultiesassociated with high rates of attrition (lack of attrition resistance)are experienced during use in reactions involving conditions of highstress. An attrition rate less than 0.5 weight percent/hour, aspreviously noted, for the compositions of this invention is preferred,with values of 0.3 weight percent/hour or less being most preferred.

The specific surface area value desirable for a given metal/oxygencomposition depends primarily on its intended use. As an example,compositions useful in the dehydrocoupling of toluene preferably willexhibit surface area values less than 5 m² /g, with values from about0.05 m² /g and 1 m² /g being most preferred. Such values result ingreater activities and selectivities to the toluene dehydrocoupledproducts. Conversely, higher surface area compositions, especially thosehaving surface areas greater than 5 m² /g, exhibit decreasedselectivities to the toluene dehydrocoupled products as evidenced by theundesirable tendency toward increased benzene and carbon dioxideproduction during such dehydrocoupling reactions.

The surface area of the metal/oxygen compositions of this invention ismeasured according to the BET method [from Brunauer et al, Journal ofthe American Chemical Society, 60, 309-319 (1938)] described in ASTM D3663-78 using a Micromeritics Digisorb 2500 instrument. In general,however, for samples having a relatively low surface area, for example,less than 5 m² /g, krypton is preferably substituted for nitrogen as theadsorption gas for increased accuracy of measurement. Examples ofmetal/oxygen compositions of the invention may be represented by theempirical formulas Pb₁₀ Sb₃ Bi₂ O_(x) (Al₂ O₃)₇₋₂₈ and Bi₁₅₋₃₀ K₄₋₅Zr₁₋₂ O_(x) (Al₂ O₃)₁₆₋₂₉, wherein x is a number taken to satisfy theaverage valences of the metal in the oxidation states in which theyexist in the composition.

3. Transformation of Organic Compounds

The attrition resistant metal/oxygen compositions of this invention, aspreviously noted, are useful for the transformation of organic compoundsin the vapor phase. For convenience and clarity, however, the use of themetal/oxygen compositions will be described with reference to a processto oxidatively dehydrocouple toluene to produce toluene dehydrocoupledproducts, namely, stilbene and bibenzyl. As noted previously, suchcompositions preferably exhibit an attrition rate less than 0.5 weightpercent/hour and, for use in the toluene dehydrocoupling process hereindescribed, a surface area less than 5 m² /g.

The attrition resistant metal/oxygen compositions of this inventionfunction in a catalytic mode, a stoichiometric mode as an oxidant oroxygen carrier, or a combined catalytic/stoichiometric mode for thedehydrocoupling of toluene.

In the catalytic mode of operation, oxygen or an oxygen-containing gassuch as air or oxygen-enriched air is reacted with toluene in thepresence of the attrition resistant metal/oxygen composition in anamount sufficient for the dehydrocoupling reaction. In thestoichiometric mode of operation, the attrition resistant metal/oxygencomposition is the sole source of oxygen. That is, in the latterinstance the dehydrocoupling of toluene is conducted in the substantialabsence of added free oxygen such as would be obtained from air. In thecombined catalytic/stoichiometric mode of operation, oxygen or anoxygen-containing gas is added as a reactant in a manner similar to thatnoted previously for the catalytic mode of operation. However, theamount of added oxygen is not sufficient for the dehydrocouplingreaction and the required additional oxygen must be supplied by theattrition resistant metal/oxygen composition.

Of these three modes of operation, the stoichiometric mode is generallypreferred in that undesirable side reactions--oxidative dealkylation,for example, to product benzene and carbon dioxide--are substantiallyreduced. It will, of course, be recognized that in spite of theundesirability of producing benzene during the course of the toluenedehydrocoupling reaction, benzene is a valuable article of commerce. Itis therefore highly desirable to recover the benzene values whensubstantial production thereof occurs. The recovery and purification ofsuch benzene values may be accomplished by any standard method and meansknown to the art.

The term "dehydrocoupling" and related terms are employed herein to meanthe toluene molecules are coupled or dimerized--with carbon-carbon bondformation occurring between the methyl group carbons--and the coupledmolecules have lost either one or two hydrogen atoms from the methylgroup of each toluene molecule. When two hydrogen atoms per molecule oftoluene are lost, the carbon-carbon bond at the coupling or dimerizationsite is unsaturated as by dehydrogenation. That is, stilbene is theproduct. On the other hand, bibenzyl, having a saturated carbon-carbonbond at the coupling site, is the product when only one hydrogen atomper molecule of toluene is lost.

In general, the production of stilbene as the toluene dehydrocoupledproduct is preferred over the production of bibenzyl. This statedpreference is due to the unsaturated character of stilbene as opposed tothe saturated character of bibenzyl. And, as is well known in the art,the presence of the unsaturated olefinic carbon-carbon double bondcauses the stilbene to exhibit high reactivity, thereby facilitating itsdirect use as an organic intermediate in numerous organic syntheses.

The toluene dehydrocoupling process using the attrition resistantmetal/oxygen compositions of this invention is conveniently carried outin an apparatus of the type suitable for carrying out chemical reactionsin the vapor phase. It can be conducted in a single reactor or inmultiple reactors using either a fixed bed, a moving bed, or a fluidizedbed system to effect contacting of the reactant or reactants and theattrition resistant metal/oxygen composition. In general, a fluidizedbed system is preferred in that it advantageously possesses the abilityto approach isothermal conditions during the course of the reactionprocess. Moreover, the attrition resistant metal/oxygen compositions ofthis invention are particularly suited for use in a fluidized bed systemdue to the low attrition rate and small particle size (mean particlesize from about 10 μm to about 200 μm). It would be apparent, of course,that when using a fluidized bed system, fluid velocities (linear gasvelocities) must be sufficient to maintain a uniform suspension of theparticles of the attrition resistant metal/oxygen composition, butinsufficient to sweep the particles out of the reactor. Gas velocitiesin the range between about 1.52 cm/sec (0.05 ft/sec) to about 91.44cm/sec ( 3.0 ft/sec) are usually sufficient, depending on factors suchas the relative densities of the gas and solid, gas viscosity, the sizeand shape of the solid particles, the number of particles per unitvolume (bed density), the size and configuration of the reactor, and thelike.

Regardless of the particular type of reactor employed--whether fixedbed, moving bed, or a fluidized bed system--the reactant toluene willgenerally be heated and introduced to the reactor as a vapor. However,the reactant may be introduced to the reactor as a liquid and thenvaporized.

The oxidative dehydrocoupling reaction is carried out in the vapor phaseand under the influence of heat. The temperature range under which thereaction can be carried out ranges from about 450° C. to about 650° C.and preferably is conducted at from about 500° C. to about 600° C., mostpreferably at about 575° C.

Pressure is not critical in the toluene dehydrocoupling process of thisinvention. The reaction may be carried out at subatmospheric,atmospheric, or superatmospheric pressures as desired. It will begenerally preferred, however, to conduct the reaction at or nearatmospheric pressure. Generally, pressures from about 2.53×10⁴ pascalsor Pa (0.25 atmosphere or atm) to about 4.05×10⁵ Pa (4.0 atm) may beconveniently employed.

The reaction time for the contact of the reactant with the attritionresistant metal/oxygen compositions of this invention may be selectedfrom a broad operable range which may vary from about 0.1 to about 60seconds. The reaction time may be defined as the length of time inseconds which the reactant gases measured under reaction conditions arein contact with the attrition resistant metal/oxygen composition in thereactor. The reaction time may vary depending upon the reactiontemperature and the desired toluene conversion level. At highertemperatures and lower toluene conversion levels, shorter contact timesare required. Generally, the contact time will vary from about 0.5seconds to about 20 seconds. Preferably, for optimum conversion andselectivity in the preferred temperature range, a contact time fromabout 1 second to about 12 seconds is employed.

In addition to the toluene, other inert substances such as nitrogen,helium, and the like may be present in the reactor. Such inert materialsmay be introduced to the process alone or may be combined with the othermaterials as feed. Water or steam may be added to the reaction zone,preferably being introduced with the feed in order to improve theselectivity to the desired product(s) and particularly to suppresscomplete oxidation to CO₂. Steam/hydrocarbon mole ratios in the rangefrom about 0.1 to about 10 or more are suitable, the upper limit beingdetermined by practical cost considerations. Mole ratios in the rangefrom about 0.5 to about 3 are preferred.

The attrition resistant metal/oxygen compositions of this inventioncontain oxygen in such a manner that they are capable of releasingstoichiometric quantities of oxygen under the oxidative reactionconditions employed to dehydrocouple toluene as described hereinbelow.The oxygen in the compositions is associated with the metals as oxides,as oxygen complexes, or as mixtures of oxides and complexes.

As previously noted, the dehydrocoupling reaction may be conducted inthe presence or absence of added free oxygen. When oxygen is not addedto the system, that is, the reaction is conducted in the stoichiometricmode of operation, the oxygen required for the reaction is provided bythe metal/oxygen composition which enters into the reaction and isconsequently reduced (or, in actual practice, partially reduced) duringthe course of the reaction. This necessitates regeneration orreoxidation which can be easily effected by heating the material in airor oxygen at temperatures from about 500° C. to about 650° C. for aperiod of time ranging from about 5 seconds to about 1 hour. In asemicontinuous operation, regeneration can be effected by periodicinterruption of the reaction for reoxidation of the reduced composition,that is, periods of reaction are cycled with periods of regeneration.Operation, however, can be on a continuous basis whereby a portion ofthe attrition resistant metal/oxygen composition can be continuously orintermittently removed, reoxidized, and the reoxidized material canthereafter be continuously or intermittently returned to the reaction.The latter method is particularly adapted to operations in which theattrition resistant metal/oxygen composition is employed in the form ofa moving bed or the preferred fluidized bed.

When oxygen is employed as a reactant, the reaction may be conducted ineither a catalytic mode of operation or a combinedcatalytic/stoichiometric mode of operation, depending on the amount ofoxygen supplied. In the catalytic mode of operation, oxygen is suppliedin an amount sufficient for the dehydrocoupling reaction. The actualamount of oxygen supplied may be specified as a function of the amountof the toluene. On this basis, the amount of oxygen supplied isordinarily selected to provide a toluene/oxygen mole ratio from about 1to about 8 and preferably from about 2 to about 6.

In the combined catalytic/stoichiometric mode of operation, the amountof oxygen supplied as a reactant is not sufficient for thedehydrocoupling reaction, thereby requiring an additional source ofoxygen. The required additional oxygen will be supplied by the attritionresistant metal/oxygen composition, that is, the composition will serveas the additional source of oxygen. As a result, the attrition resistantmetal/oxygen composition enters into the reaction and is consequentlyreduced during the course of the reaction. This necessitatesregeneration or reoxidation of the reduced composition which can beeasily effected as described previously for the stoichiometric mode ofoperation.

In either mode of operation employing added oxygen as a reactant,whether catalytic or combined catalytic/stoichiometric, the added freeoxygen may be supplied either as oxygen or an oxygen-containing gas suchas air or oxygen-enriched air.

As previously indicated, the toluene dehydrocoupling process employingthe attrition resistant metal/oxygen compositions of this invention ispreferably carried out in the absence of added free oxygen, that is, inthe stoichiometric mode of operation, and utilizes only that oxygensupplied by the attrition resistant metal/oxygen composition. Also, withfew exceptions, at substantially comparable conditions, the lower thetoluene conversion level, the higher will be the selectivity to thedehydrocoupled products. That is, under similar conditions, theselectivity to the dehydrocoupled toluene product is in generalinversely proportional to the toluene conversion level. However, forpractical reasons, the dehydrocoupling reaction will generally beconducted at a toluene conversion level of about 20 to about 55 percent.

The toluene dehydrocoupled products, stilbene and bibenzyl, may berecovered and purified by an appropriate method and means known to theart and further elucidation here will be unnecessary duplication of theart. As noted previously, stilbene, of course, if the preferred product.

The following specific examples illustrating the best presently knownmethods of practicing the invention are described in detail in order tofacilitate a clear understanding of the invention. It should beunderstood, however, that the detailed expositions of the application ofthe invention, while indicating preferred embodiments, are given by wayof illustration only and are not to be construed as limiting theinvention since various changes and modifications within the spirit ofthe invention will become apparent to those skilled in the art from thisdetailed description.

EXAMPLE 1 Alumina Preparation

The alumina was sieved for 30 minutes. The material less than 120 mesh(U.S. Standard Sieve Size; 125 μm) or 70 mesh (200 μm), as indicated,and larger than 400 mesh (38 μm), 325 mesh (45 μm), or 200 mesh (75 μm),as indicated, was retained. The retained material was sieved twice moreon clean mesh screens of the previously indicated size. Each time the-20, +400 (120/400), -70, +325 (70/325), or -70 , +200 (70/200) meshmaterial, as indicated, was retained. A sufficient quantity of thetriply sieved alumina was accurately weighed for use in preparing theattrition resistant metal/oxygen compositions.

Properties of numerous representative aluminas (Al₂ O₃) are tabulated inTable 1.

                                      TABLE 1                                     __________________________________________________________________________    REPRESENTATIVE ALUMINAS AND PROPERTIES.sup.1                                  __________________________________________________________________________                     CRYSTAL PHASE.sup.2                                                                           WATER   PARTICLE SIZE DISTRIBUTION,                                                   %.sup.4                              SAMPLE                                                                              BRAND              AFTER 2 HR                                                                            (CHEMICAL)                                                                            μm                                NO.   IDENTIFICATION                                                                           INITIAL @ 550° C.                                                                      Wt. %.sup.3                                                                           <20 20-45                                                                              45-88                                                                             88-125                                                                             >125               __________________________________________________________________________    1-A   Alcoa FAH (SF-30).sup.11                                                                 Boehmite and                                                                          α and χ                                                                     6.5     11  3    25  28   33                                  Gibbsite                                                     1-B   Calsicat   δ and θ                                                                   δ and θ                                                                   1.0     5   26   52  13   4                        49B-048A.sup.12                                                         1-C   Catapal SB.sup.13                                                                        α and Boehmite                                                                  α and γ                                                                   14.5    12  20   36  22   10                 1-D   Harshaw 1465P.sup.14                                                                     γ γ 2.0     9   24   49  12   6                  1-E   Harshaw 3970P.sup.14                                                                     γ γ 2.4     2   22   44  22   10                 1-F   Kaiser A-300.sup.15                                                                      χ   χ   5.0     12  24   30  24   10                 1-G   Ketjen D.sup.16                                                                          Boehmite                                                                              γ 14.5    12  33   50  4    1                  1-H   Ketjen M.sup.16                                                                          Boehmite                                                                              γ 14.5    8   15   43  21   13                 1-I   Norton SA6373.sup.17                                                                     Boehmite                                                                              γ 12.0    12  11   20  44   13                 1-J   Norton 74368.sup.17                                                                      Boehmite                                                                              γ 7.0     2   35   55  15   5                  1-K   Norton 74380.sup.17                                                                      Boehmite                                                                              γ and χ                                                                     8.1     11  28   52  7    2                  1-L   Alcoa F-1-100.sup.11                                                                     γ and Boehmite                                                                  γ 14.8    7.5 22.5 40  23.7 6.3                __________________________________________________________________________    SAMPLE                                                                              BET          DENSITY, g/cc       POROSITY.sup.9 MEAN PORE               NO.   SURFACE AREA, m.sup.2 /g.sup.5                                                             PARTICLE.sup.6                                                                       SKELETAL.sup.7                                                                        BULK.sup.8                                                                         FRACTIONAL.sup.10                                                                      % <55 A.sup.9                                                                       DIAMETER,               __________________________________________________________________________                                                          A.sup.9                 1-A   151.5        1.78   3.27    1.23 0.455    76.1  37.5                    1-B    91.1        1.42   3.57    0.72 0.602     1.0  125.0                   1-C   226.0        1.15   3.48    0.99 0.670    16.3  67.5                    1-D   147.8        1.42   3.35    0.89 0.576    11.0  77.5                    1-E   196.5        1.18   3.56    0.86 0.669    14.5  72.5                    1-F   154.9        1.68   3.27    1.21 0.486    74.0  47.5                    1-G   257.4        1.04   3.29    0.90 0.684    44.0  57.5                    1-H   280.0        1.27   3.12    1.00 0.593    47.0  62.5                    1-I   235.0        1.38   3.65    0.94 0.622    42.1  57.5                    1-J   206.0        1.16   3.28    0.82 0.646    16.6  72.5                    1-K   186.0        1.60    3.075  0.80 0.480    80.0  57.5                    1-L   210.0        1.44   3.43    0.88 0.580    69.7  42.5                    __________________________________________________________________________     .sup.1 Physical property measurements were performed on heat treated          aluminas (after 2 hours at 550° C.).                                   .sup.2 Analyses were performed using a Philips Diffractometer.                .sup.3 Determined by heating an accurately weighed sample to constant         weight and by differential thermal analysis (DTA).                            .sup.4 Measured according to the manufacturer's procedure using a Leeds &     Northrup Microtrak instrument.                                                .sup.5 Measured according to ASTM D 366378 for surface area of catalysts      using a Micromeritics Digisorb 2500 instrument.                               .sup.6 Measured by mercury displacement using an AmincoWinslow                Porisimeter.                                                                  .sup.7 Determined using a Micromeritics Helium Pycnometer.                    .sup.8 Determined by accurately weighing a given volume of compacted          material.                                                                     .sup.9 Determined by nitrogen desorption using a Micromeritics Digisorb       2500 instrument.                                                              .sup.10 Calculated using the mathematical relationship,                       ##STR1##                                                                      where F.P. is the fractional porosity, ρ.sub.He is the skeletal           density, and ρ.sub.He is the particle density.                            .sup.11 Available commercially from Aluminum Company of America, 1501         Alcoa Bldg., Pittsburgh, PA 15219.                                            .sup.12 Obtained from Mallinckrodt, Inc., Calsicat Div., 1707 Gaskell         Ave., Erie, PA 16508. Not commercially available. Included for comparativ     purposes.                                                                     .sup.13 Available commercially from Conoco Chemicals Company, P.O. Box        2197, Houston, TX 77001.                                                      .sup.14 Available commercially from Harshaw Chemical Company, 1945 East       97th Street, Cleveland, OH 44106.                                             .sup.15 Available commercially from Kaiser Chemicals Company, 300 Lakesid     Dr., Oakland, CA 94643.                                                       .sup.16 Available commercially from Akzo Armak Company (Agent), 300 So.       Wacker Dr., Chicago, IL 60606.                                                .sup.17 Available commercially from Norton Company, 1 New Bond St.,           Worcester, MA 01606.                                                     

EXAMPLES 2-43 General

A series of attrition resistant metal/oxygen compositions were preparedby intimately mixing the appropriate quantities of at least one metaloxide and an alumina, heating to a temperature and for a time sufficientto remove any added wetting agent and physically bound water, as well asother volatitle components, and calcining the mixture. The calcinedmaterial was cooled under controlled cool-down conditions and sieved tothe size of the original alumina. The retained material accounted forgreater than 90 weight percent of the calcined metal/oxygen composition.The metal/oxygen compositions were further characterized as described inExamples 44 (attrition rate) and 45 (transformation of organiccompounds, with the dehydrocoupling of toluene being used forillustrative purposes).

EXAMPLES 2-10

The following is a general procedure for the preparation of ametal/oxygen composition using a wetting agent (wet mixing process) andcontaining bismuth, calcium, and zirconium. (Example 3 is included as acomparative example to show an alumina outside the scope of the presentinvention.)

To a suitably sized wide-mouthed, polyethylene jar was added appropriatequantities of bismuth (III) oxide (Bi₂ O₃), calcium oxide (CaO), andzirconium (IV) oxide (ZrO₂), all as powders, and a sufficient number ofsuitably sized alumdum balls [6-8 1.9-centimeter (0.75 inch) diameterfor a 4.4-liter (1-gallon, dry) jar]. The jar was placed on a ball milland the contents ball milled for 6 hours. The thoroughly mixed metaloxide powders and a sufficient quantity of the triply sieved alumina (inaccordance with the procedure described in Example 1, above) were placedin a second suitably sized wide-mouthed, polyethylene jar without thealumdum balls. The alumina/metal oxides mole percent ratio wasapproximately 55/45. The jar was shaken by hand for 5 minutes and thenrotated on a ball mill for 3 hours. The resultant mixture was passedthrough a 100 mesh (U.S. Standard Sieve Size) screen to insure mixing.Any clumps remaining on the screen were broken up and passed through thescreen. The sieved mixture was returned to the jar and rotated on theball mill an additional 3 hours if any clumps remained on the screenafter sieving, or, in the absence of any remaining clumps, for only 0.5hour to break up any stratification of powders resulting from sieving.

To the dry-mixed components was added sufficient water, with stirring byhand, to form a thixotropic paste. The paste was placed in suitablysized fused alumina crucibles containing less than 0.2% silica to amaximum depth of 7.62 centimeters (3.0 inches). The loaded crucibleswere placed in an air-purged furnace. The furnace was heated to150°-250° C., usually 200° C., which temperature was maintained for 1hour to 5 hours, usually 5 hours, to remove the excess wetting agent.The temperature was then increased to 1000° C. at a rate of 120° C. perhour (slow heat-up). Calcination was continued at 1000° C. for about 10hours. After the calcination was complete, the metal/oxygen compositionwas cooled to 700° C. under controlled conditions at a maximum cool-downrate of 150° C. per hour. Thereafter, the cool-down was continued at itsnatural rate to ambient temperature.

The cooled, lightly agglomerated metal/oxygen composition was crushedand sieved for 30 minutes to complete the breakdown of the softagglomerations to 120/400, 70/325, or 70/200 mesh particles, dependingupon which corresponded to the original particle size of the aluminastarting material. The retained material had a uniformly yellow color.The parameters for such compositions are set forth in Table 2, below.

EXAMPLES 11-19

The following is a general procedure for the preparation of ametal/oxygen composition in the absence of a wetting agent (dry mixingprocess) and containing lead, antimony, and bismuth. (Example 12 isincluded as a comparative example to show an alumina outside the scopeof the present invention.)

The procedure described above for the wet mixing process (Examples 2-10)was employed through the dry-mixing steps using appropriate quantitiesof lead (II) oxide (PbO), antimony (III) oxide (Sb₂ O₃), bismuth (III)oxide (Bi₂ O₃), and alumina. The alumina/metal oxides mole percent ratiowas 51.3/48.7. The thoroughly mixed components were placed in suitablysized fused alumina crucibles containing less than 0.2% silica andcompacted to insure close physical contact. The maximum depth of loadingwas 7.62 centimeters (3.0 inches) to permit air to diffuse the materiallocated at the bottom of the crucible during the air calcination. Theloaded crucibles were placed in a nitrogen-purged furnace. The furnace,under a constant nitrogen purge, was heated to 150°-250° C., usually200° C., which temperature was maintained for 1 hour to 5 hours, usually2 hours, to remove any physically bound water. The temperature was thenincreased to 1000° C. over a 1-hour period (rapid heat-up) in order todelay the oxidation of antimony (III) oxide to antimony (V) oxide untilthe air calcination period. Calcination was continued at 1000° C. undera nitrogen purge for about 1 hour. The furnace atmosphere was changed toair and calcination continued under an air purge for an additional 9hours. The calcined metal/oxygen composition, a uniformly burnt orangecolor, was then treated as described in Examples 2-10, above. Theparameters for such compositions are set forth in Table 2, below.

EXAMPLES 20-34

The following illustrates the preparation of a number of metal/oxygencompositions containing a number of different elements.

The metal/oxygen compositions were prepared according to the wet mixingprocess procedure described in Examples 2-10, above, except that rapidheat-up to the calcination temperature as described in Examples 11-19,above, was employed for those compositions using antimony (III) oxide asa starting material. The parameters for such compositions are set forthin Table 2, below.

EXAMPLES 35-36

A number of metal/oxygen compositions were prepared according to the drymixing process procedure described in Examples 11-19, above. Theparameters for such compositions are set forth in Table 2, below.

EXAMPLE 37

The following procedures illustrate the preparation of a metal/oxygencomposition containing bismuth. The parameters for such compositions areset forth in Table 2, below.

Procedure A--Bismuth (III) oxide (Bi₂ O₃, 200.7 grams, 0.43 mole) wasball milled for 6 hours and dry mixed with 97.2 grams (0.90 mole) of120/400 mesh alumina (Sample No. 1-F) as described in Examples 11-19,above. The Al₂ O₃ /Bi₂ O₃ mole percent ratio was 67.7/32.3. The mixturewas heated in air at 200° C. for 1 hour to remove any physically boundwater, followed by 450° C. for 1 hour to remove any other volatilecomponents, and then calcined at 850° C. for 5 hours. The metal/oxygencomposition was cooled to 700° C. at a maximum cool-down rate of 150° C.per hour. Thereafter, the cool-down was continued at its natural rate toambient temperature.

The cooled, lightly agglomerated metal/oxygen composition was crushedand sieved for 30 minutes to complete the breakdown of the softagglomerations to -120 mesh particles. The metal/oxygen composition wasthen heated in air at 200° C. for 1 hour, followed by 450° C. for 1 hourto remove, respectively, any physically bound water and other volatilecomponents, and recalcined at 850° C. for 1 hour and 1000° C. for 4hours. Cool-down was carried out as previously described. The materialwas crushed and sieved for 30 minutes to complete the break-down of thesoft agglomeration to 120/400 mesh particles which particle sizecorresponds to the original particle size range of the alumina.

Procedure B--Procedure A, above, was repeated except that the materialswere wet mixed and dried as described in Examples 2-10, above.

Procedure C--Procedure A, above was repeated except that after theinitial heating, calcination, cool-down, and sieving, the metal/oxygencomposition was heated at 200° C. for 1 hour, followed by 450° C. for 1hour to remove, respectively, any physically bound water and othervolatile components, and calcined at 650° C. for 1.5 hours, 850° C. for1.5 hours, and 900° C. for 4 hours.

Procedure D--Procedure A, above, was repeated using 200.0 grams (0.43mole) of Bi₂ O₃ and 86.0 grams (0.80 mole) of 120/400 mesh Al₂ O₃(Sample 1-F). The Al₂ O₃ /Bi₂ O₃ mole percent ratio was 65/35.

Procedure E--A metal/oxygen composition having an Al₂ O₃ /Bi₂ O₃ molepercent ratio of 69.7/30.3 was prepared in accordance with Procedure A,above, using 186.4 grams (0.40 mole) of Bi₂ O₃ and 98.4 grams (0.92mole) of 120/400 mesh Al₂ O₃ (Sample 1-F).

Procedure F--A metal/oxygen composition having an Al₂ O₃ /Bi₂ O₃ molepercent ratio of 66/34 was prepared in accordance with Procedure B,above, using 400.0 grams (0.86 mole) of Bi₂ O₃ and 179.8 grams (1.67moles) of 120/400 mesh Al₂ O₃ (Sample 1-F).

EXAMPLE 38

The following procedures illustrate the preparation of metal/oxygencompositions containing bismuth, potassium, and zirconium. Theparameters for such compositions are tabulated in Table 2, below.

Procedure A--An aqueous solution of 3.9 grams (0.070 mole) of potassiumhydroxide (KOH) dissolved in the minimum amount of water was slurriedwith 24.3 grams (0.23 mole) of 120/400 mesh alumina (Sample No. 1-F) andheated to dryness. The dry mixture was dry-mixed with 48.9 grams (0.10mole) of bismuth (III) oxide (Bi₂ O₃) and 1.7 grams (0.014 mole) ofzirconium (IV) oxide (ZrO₂) as described in Examples 11-19, above. TheAl₂ O₃ /metal oxides mole percent ratio was 54.9/45.1. The dry mixturewas heated in air at 500° C. for 1 hour to remove any physically boundwater and other volatile components and calcined at 750° C. for 1 hourand 1000° C. for 9 hours. The metal/oxygen composition was cooled toambient temperature and sieved as described in Example 37, Procedure A,above.

Procedure B--Procedure A, above, was repeated except that the materialswere wet-mixed and dried as described in Examples 2-10, above. The drymixture was heated in air at 500° C. for 1 hour to remove any physicallybound water and other volatile components and then calcined at 1000° C.for 10 hours.

Procedure C--To an aqueous solution of 3.9 grams (0.070 mole) ofpotassium hydroxide dissolved in the minimum amount of water was added apreviously ball-milled mixture of 48.9 grams (0.10 mole of bismuth (III)oxide and 1.7 grams (0.014 mole) of zirconium (IV) oxide and thoroughlymixed. The mixture was heated to dryness at 200° C. in an air-purgedfurnace over a 2-hour period, followed by further heating at 450° C. for1 hour and 600° C. for 16 hours. The resultant material was ground to avery fine powder and dry mixed with 24.3 grams (0.23 mole) of 120/400mesh alumina (Sample No. 1-F) as described in Examples 11-19, above. Themixture was heated at 450° C. for 1 hour to remove any physically boundwater and other volatile components, and thereafter calcined in air at750° C. for 0.5 hour, followed by 1000° C. for 10 hours.

EXAMPLE 39

The following procedure illustrates the preparation of a metal/oxygencomposition containing bismuth, calcium, and zirconium. The parametersfor the composition are tabulated in Table 2, below.

To an aqueous slurry of 48.9 grams (0.105 mole) of bismuth (III) oxide,3.9 grams (0.070 mole) of calcium oxide, and 1.7 grams (0.014 mole) ofzirconium (IV) oxide, which had been previously dry mixed as describedin Examples 11-19, above, was added 24.3 grams (0.23 mole) of 120/400mesh alumina (Sample No. 1-F). The Al₂ O₃ /metal oxides mole percentratio was 54.9/45.1. The slurry was heated to dryness as described inExamples 2-10, above, and thereafter heated at 450° C. for 1 hour toremove any volatile components present. The mixture was then calcined at1000° C. for 10 hours. The composition was cooled and sieved asdescribed in Examples 2-10, above.

EXAMPLE 40

The following procedure illustrates the preparation of a metal/oxygencomposition containing bismuth, potassium, and zirconium, and usingmethanol as a wetting agent. The parameters of the composition are setforth in Table 2, below.

To a methanolic solution of 101.9 grams (1.55 moles) of 85% potassiumhydroxide (KOH) dissolved in 400 milliliters of methanol was added a drymixed mixture (prepared as described in Examples 11-19, above) ofreagent grade bismuth (III) oxide (Bi₂ O₃, 1269.7 grams, 2.72 moles)zirconium (IV) oxide (Zro₂, 44.8 grams, 0.36 mole), and 120/400 meshalumina (Al₂ O₃, 634.8 grams, 5.90 moles, Sample No. 1-F) to form athixotropic paste. Sufficient methanol was added to ensure good mixing.The Al₂ O₃ /metal oxides mole percent ratio was 56.1/43.9. The paste wasloaded into suitably sized fused alumina crucibles and placed in anair-purged furnace. The paste was heated to 970° C. at the rate of 2° C.per minute (slow heat-up). Calcination was continued at 970° C. for 10hours. After the calcination was complete, the metal/oxygen compositionwas cooled to ambient temperatures and sieved to 120/400 mesh particlesas described in Examples 2-10, above.

EXAMPLE 41

The following procedure illustrates the preparation of a metal/oxygencomposition containing bismuth, potassium, and zirconium.

To an aqueous solution of 101.1 grams (1.00 mole) of potassium nitratedissolved in 1000 milliliters of water was added a dry mixed mixture(prepared as described in Examples 11-19 above) of reagent grade bismuth(III) oxide (Bi₂ O₃, 1398,0 grams, 3.00 moles), zirconium (IV) oxide(ZrO₂, 49.3 grams, 0.40 mole), and 120/400 mesh alumina (Al₂ O₃, 738.2grams, 6.19 moles, Sample No. 1-H) to form a thixotropic paste.Sufficient water was added to ensure good mixing. The Al₂ O₃ /metaloxides mole percent ratio was 56.6/43.4. The paste was loaded intosuitably sized fused crucibles to about one-third capacity and placed inan air-purged furnace. The paste was dried at 200° C. for 5 hours andcalcined at 1000° C. for 10 hours, and the composition cooled to ambienttemperatures and sieved to 120/400 mesh particles as described inExamples 2-10, above.

EXAMPLE 42

The following procedure illustrates the preparation of a metal/oxygencomposition containing bismuth, iron, calcium, and boron. The parametersfor the composition are set forth in Table 2, below.

Reagent grade bismuth (III) oxide (Bi₂ O₃, 233.2 grams, 0.50 mole), iron(III) oxide (Fe₂ O₃, 80.0 grams, 0.50 mole), calcium oxide (CaO, 56.0grams, 1.0 mole), boric acid (H₃ BO₃, 12.4 grams, 0.20 mole) werethoroughly mixed by grinding together in a mortar. The resultant mixturewas dry mixed with 160.0 grams (1.57 moles) of 120/400 mesh alumina(Sample 1-F) by physically stirring until a uniform mixture wasobtained. The Al₂ O₃ /metal oxides mole percent ratio was 41.6/58.4. Themixture was divided equally among four 7.62-centimeter (3.0-inch)diameter and 2.54-centimeter (1.0-inch) deep fused alumina dishescontaining less than 0.2% silica and having a capacity of about 80milliliters. The material was compacted to ensure close physicalcontact. The shallow loading depth permitted air to diffuse the materiallocated at the bottom of the dishes during the air calcination.

The loaded dishes were placed in an air-purged furnace and the mixtureheated at 150° C. for 1 hour to remove any physically bound water,followed by 450° C. for 1 hour to remove any other volatile components.The mixture was then calcined at 750° C. for 1 hour, followed by 950° C.for 16 hours. The metal/oxygen composition was cooled to 700° C. at amaximum cool-down rate of 150° C. per hour and thereafter at its naturalcool-down rate to ambient temperature.

The cooled, lightly agglomerated metal/oxygen composition was crushedand sieved for 30 minutes to complete the breakdown of the softagglomerations to 120/400 mesh particles which corresponds to theoriginal particle size range of the alumina.

EXAMPLE 43

The following procedure illustrates the preparation of a metal/oxygencomposition containing bismuth, iron, and calcium, and using methanol asa wetting agent. The parameters for the composition are set forth inTable 2, below.

Reagent grade bismuth (III) oxide (Bi₂ O₃, 58.3 grams, 0.125 mole), iron(III) oxide (Fe₂ O₃, 20.0 grams, 0.125 mole), and calcium oxide (CaO,14.0 grams, 0.25 mole) as the metal oxides and 120/400 mesh alumina (Al₂O₃, 40.0 grams, 0.39 mole, Sample No. 1-F) were thoroughly mixed asdescribed in Example 40, above. The Al₂ O₃ /metal oxide mole percentratio was 44/56. To the dry-mixed components was added sufficientmethanol, with stirring by hand, to form a thixotropic paste. The pastewas placed into a 7.62-centimeter (3.0 inch) diameter and2.54-centimeter (1.0-inch) deep fused alumina dish containing less than0.2% silica and having a capacity of 80 milliliters. The paste washeated, with stirring, to dryness on a hotplate. The shallow loadingdepth of the dry material permitted air to diffuse the material locatedat the bottom of the dish during air calcination. The loaded dish wasplaced in an air-purged furnace and the mixture heated, calcined to formthe metal/oxygen composition, cooled, and sieved as described in Example42, above.

EXAMPLE 44

This Example illustrates the accelerated attrition test used todetermine attrition rate of the attrition resistant metal/oxygencompositions of this invention.

The apparatus used to determine the attrition rate is described inHoudry Catalyst Brochure, Air Products and Chemicals, Inc., "FCCCatalyst Retention is Better with Houdry® HFZ™ & HEZ™ Catalysts," 1977.It consisted of a stainless steel tube 69.85 centimeters (27.5 inches)in length and 3.81 centimeters (1.5 inches) in inside diameter connectedthrough a cone [10.16-centimeter (4-inch) rise] to a stainless steeltube 45.72 centimeters (18 inches) in length and 12.7 centimeters (5inches) in inside diameter which had a flanged opening at the upper end.

The upper end was capped with a 0.64-centimeter (0.25-inch) thickstainless steel plate having a tubular opening in the center 3.81centimeters (1.5 inches) in length and 0.95 centimeter (0.38 inch) ininside diameter. The plate was bolted onto the flange through eight0.48-centimeter (0.19-inch) diameter holes machined into its outerperimeter and sealed with a neoprene gasket. Attached to the center-tubeopening was a 250-milliliter filter flask, which had an extractionthimble attached to its side arm. A perforated stainless steel platecontaining three equally spaced 0.041-centimeter (0.016-inch) diameterholes was located at the bottom of the stainless steel tube. Connectedto the bottom of the stainless steel tube was air inlet means containingpressure regulators and flow controllers. The filter flask and theextraction thimble assembly was conditioned by passing humidified airthrough it for 30 minutes and then weighed. A sample of the composition(from Examples 2-43) was screened using a 125/400 mesh sieve (U.S.Standard Sieve Size) to remove any dust and fines. A 50 -millilitersample of the screened composition was accurately weighed and charged tothe apparatus described above. Humidified air was introduced through theperforated plate at the bottom of the stainless steel tube at a linearvelocity of about 3.048×10⁴ cm/sec (1×10³ ft/sec) to fluidize thecomposition.

After 5 hours, the flask and thimble assembly (first flask and thimbleassembly) was replaced with another conditioned flask and thimbleassembly (second flask and thimble assembly). The first flask andthimble assembly was weighed to determine the weight in grams of dustand fines associated with weak particles, dust, and trash alreadypresent in the composition. The fluidization was continued for anadditional 16 hours for a total of 21 hours. At the end of this period,the second flask and thimble assembly was weighed to determine theweight in grams of dust and fines resulting from attrition during theprolonged fluidization. The attrition rate, as weight percent/hour, wascalculated as follows: ##EQU3## The attrition rate is shown in Table 2under the column headed "Attrition Rate, Wt. % Hour."

                                      TABLE 2                                     __________________________________________________________________________    METAL OXIDE(S)                      ALUMINA.sup.1                                                          MEAN                    PARTICLE                 EX-                          PARTICLE                SIZE, μm.sup.2        AMPLE                                                                              GRAMS                                                                              (MOLES)      MOLE %                                                                              SIZE, μm.sup.2                                                                    GRAMS                                                                              (MOLES)                                                                             MOLE %                                                                              RANGE                                                                              MEAN                __________________________________________________________________________     2   201.7                                                                              (0.43)                                                                              Bi.sub.2 O.sub.3                                                                     24.9  10     103.1                                                                              1-A   55.0  38-125                                                                             90                       16.2 (0.29)                                                                              CaO    16.8  6  9.5.sup.6                                                                              (0.95)                                    7.1  (0.058)                                                                             ZrO.sub.2                                                                            3.4   4                                                  3*            "            "  "   97.4 1-B   "     "    56                                                           (0.95)                                4              "            "  "   112.7                                                                              1-C   "     "    68                                                           (0.95)                                5              "            "  "   98.4 1-D   "     "    60                                                           (0.95)                                6              "            "  "   99.2 1-E   "     "    62                                                           (0.95)                                7              "            "  "   101.5                                                                              1-F   "     "    77                                                           (0.95)                                8              "            "  "   112.7                                                                              1-G   "     "    50                                                           (0.95)                                9              "            "  "   112.7                                                                              1-H   "     "    74                                                           (0.95)                               10              "            "  "   104.2                                                                              1-J   "     "    93                                                           (0.95)                               11   160.2                                                                              (0.72)                                                                              PbO    38.9  8      103.1                                                                              1-A   51.3  "    90                       31.4 (0.11)                                                                              Sb.sub.2 O.sub.3                                                                     5.9   3  7.6.sup.6                                                                              (0.95)                                    33.4 (0.072)                                                                             Bi.sub.2 O.sub.3                                                                     3.9   10                                                 12*           "            "  "   97.4 1-B   "     "    56                                                           (0.95)                                                                              2 O.sub.3  10                  13              "            "  "   112.7                                                                              1-C   "     "    68                                                           (0.95)                                                                              2 O.sub.3  10                  14              "            "  "   98.4 1-D   "     "    60                                                           (0.95)                                                                              2 O.sub.3  10                  15   160.2                                                                              (0.72)                                                                              PbO    38.9  8      99.2 1-E   51.3  38-125                                                                             62                       31.4 (0.11)                                                                              Sb.sub.2 O.sub.3                                                                     5.9   3  7.6.sup.6                                                                              (0.95)                                    33.4 (0.072)                                                                             Bi.sub.2 O.sub.3                                                                     3.9   10 "                                             16              "            "  "   101.5                                                                              1-F   "     "    77                                                           (0.95)                                                                              2 O.sub.3  10                  17              "            "  "   112.7                                                                              1-G   "     "    50                                                           (0.95)                                                                              2 O.sub.3  10                  18              "            "  "   112.7                                                                              1-H   "     "    74                                                           (0.95)                                                                              2 O.sub.3  10                  19              "            "  "   104.2                                                                              1-J   "     "    93                                                           (0.95)                                                                              2 O.sub.3  10                  20   50.2 (0.22)                                                                              PbO    36.4  8  7.2.sup.6                                                                         40.0 1-I   57.9  75-200                                                                             97                       9.8  (0.034)                                                                             Sb.sub.2 O.sub.3                                                                     5.6   3           (0.35)                               21   94.9 (0.20)                                                                              Bi.sub.2 O.sub.3                                                                     27.4  10 9.2.sup.6                                                                         45.0 1-I   53.4  "    97                       10.1 (0.14)                                                                              NiO    19.2  2.sup.9     (0.39)                               22   33.1 (0.44)                                                                              CoO    41.9  5.sup.9                                                                          5.0.sup.6                                                                         45.0 1-I   37.1  "    97                       71.9 (0.22)                                                                              La.sub.2 O.sub.3                                                                     21.0  5.sup.9     (0.39)                               23   42.7 (0.19)                                                                              PbO    31.4  8      40.0 1-I   57.8  45-200                                                                             93                       8.4  (0.029)                                                                             Sb.sub.2 O.sub.3                                                                     4.8   3  7.6.sup.6                                                                              (0.35)                                    8.9  (0.019)                                                                             Bi.sub.2 O.sub.3                                                                     3.1   10                                                    1.0  (0.018)                                                                             KOH    3.0   --.sup.10                                        24   42.7 (0.19)                                                                              PbO    31.3  8      40.0 1-I   57.7  75-200                                                                             97                       8.4  (0.029)                                                                             Sb.sub.2 O.sub.3                                                                     4.8   3  7.6.sup.6                                                                              (0.35)                                    8.9  (0.019)                                                                             Bi.sub.2 O.sub.3                                                                     3.1   10                                                    0.8  (0.019)                                                                             MgO    3.1   7                                                25   42.7 (0.19)                                                                              PbO    31.3  8      40.0 1-I   57.7  "    "                        8.4  (0.029)                                                                             Sb.sub.2 O.sub.3                                                                     4.8   3  7.5.sup.6                                                                              (0.35)                                    8.9  (0.019)                                                                             Bi.sub.2 O.sub.3                                                                     3.1   10                                                    1.6  (0.019)                                                                             ZnO    3.1   3                                                26   42.7 (0.19)                                                                              PbO    31.3  8      40.1 1-I   57.7  "    "                        8.4  (0.029)                                                                             Sb.sub.2 O.sub.3                                                                     4.8   3  7.6.sup.6                                                                              (0.35)                                    8.9  (0.019)                                                                             Bi.sub.2 O.sub.3                                                                     3.1   10                                                    0.5  (0.019)                                                                             LiOH   3.1   --.sup.10                                        27   60.0 (0.27)                                                                              PbO    43.5  8      40.0 1-I   56.5  "    "                                                            (0.35)                               28   49.6 (0.22)                                                                              PbO    37.2  "  8.3.sup.6                                                                         40.0 1-I   59.1  45-200                                                                             93                       10.4 (0.022)                                                                             Bi.sub.2 O.sub.3                                                                     3.7   10          (0.35)                               29   113.9                                                                              (0.51)                                                                              PbO    51.6  8      40.0 1-I   35.4  45-200                                                                             93                       22.3 (0.077)                                                                             Sb.sub.2 O.sub.3                                                                     7.8   3  7.6.sup.6                                                                              (0.35)                                    23.8 (0.051)                                                                             Bi.sub.2 O.sub.3                                                                     5.2   10                                               30   26.7 (0.12)                                                                              PbO    32.4  8      25.0 1-I   59.5  38-125                                                                             93                       5.2  (0.018)                                                                             Sb.sub.2 O.sub.3                                                                     4.9   3  7.6.sup.6                                                                              (0.22)                                    5.6  (0.012)                                                                             Bi.sub.2 O.sub.3                                                                     3.2   10                                               31   17.9 (0.080)                                                                             PbO    25.0  8      25.1 1-I   68.8  "    93                       3.5  (0.012)                                                                             Sb.sub.2 O.sub.3                                                                     3.8   3  7.6.sup.6                                                                              (0.22)                                    3.7  (0.0080)                                                                            Bi.sub.2 O.sub.3                                                                     2.5   10                                               32   285.7                                                                              (1.28)                                                                              PbO    41.4  8      172.2                                                                              1-I   48.2  75-200                                                                             97                       56.0 (0.19)                                                                              Sb.sub.2 O.sub.3                                                                     6.1   3  "        (1.49)                                    59.6 (0.13)                                                                              Bi.sub.2 O.sub.3                                                                     4.2   10                                               33   42.7 (0.19)                                                                              PbO    32.3  8      40.0 1-I   59.5  45-200                                                                             93                       8.4  (0.029)                                                                             Sb.sub.2 O.sub.3                                                                     4.9   3  "        (0.35)                                    8.9  (0.019)                                                                             Bi.sub.2 O.sub.3                                                                     3.2   10                                               34   74.5 (0.33)                                                                              PbO    41.1  8      45.0 1-I   48.6  75-200                                                                             97                       14.6 (0.050)                                                                             Sb.sub.2 O.sub.3                                                                     6.2   3  7.6.sup.6                                                                              (0.39)                                    15.6 (0.033)                                                                             Bi.sub.2 O.sub.3                                                                     4.1   10                                               35   74.5 (0.33)                                                                              PbO    41.1  8      45.0 1-I   48.6  "    "                        14.6 (0.050)                                                                             Sb.sub.2 O.sub.3                                                                     6.2   3  "        (0.39)                                    15.6 (0.033)                                                                             Bi.sub.2 O.sub.3                                                                     4.1   10                                               36   74.5 (0.33)                                                                              PbO    41.1  8      45.0 1-I   48.6  75-200                                                                             97                       14.6 (0.050)                                                                             Sb.sub.2 O.sub.3                                                                     6.2   3  7.6.sup.6                                                                              (0.39)                                    15.6 (0.033)                                                                             Bi.sub.2 O.sub.3                                                                     4.1   10                                               37-A 200.7                                                                              (0.43)                                                                              Bi.sub.2 O.sub.3                                                                     32.3  "      97.2 1-F   67.7  38-125                                                                             "                                                            (0.90)                               37-B            "            "           "           "    "                   37-C            "            "           "           "    "                   37-D 200.0                                                                              (0.43)                                                                              "      35.0  "      86.0 1-F   65.0  "    "                                                            (0.80)                               37-E 186.4                                                                              (0.40)                                                                              "      30.3  "      98.4 1-F   69.7  "    "                                                            (0.92)                               37-F 400.0                                                                              (0.86)                                                                              "      34.0  "      179.8                                                                              1-F   66.0  "    "                                                            (1.67)                               38-A 48.9 (0.105)                                                                             "      25.1  "      24.3 1-F   54.9  "    "                        3.9  (0.070)                                                                             KOH    16.7  --.sup.10                                                                        9.8.sup. (0.23)                                    1.7  (0.014)                                                                             ZrO.sub.2                                                                            3.3   4                                                38-B            "            "  "        "           "    "                   38-C            "            "  "        "           "    "                   39   48.9 (0.105)                                                                             Bi.sub.2 O.sub.3                                                                     25.1  10     24.3 1-F   54.9  38-125                                                                             77                       3.9  (0.070)                                                                             CaO    16.7  6  9.5.sup.6                                                                              (0.23)                                    1.7  (0.014)                                                                             ZrO.sub.2                                                                            3.3   4                                                40   1269.7                                                                             (2.72)                                                                              Bi.sub.2 O.sub.3                                                                     25.8  10     634.8                                                                              1-F   56.1  38-125                                                                             77                       44.8 (0.36)                                                                              ZrO.sub.2                                                                            3.4   4  9.8.sup.6                                                                              (5.90)                                    101.9                                                                              (1.55)                                                                              KOH (85%)                                                                            14.7  --.sup.10                                        41   1398.0                                                                             (3.00)                                                                              Bi.sub.2 O.sub.3                                                                     29.6  10     738.2                                                                              1-H.sup.11                                                                          56.6  "    74                       49.3 (0.40)                                                                              ZrO.sub.2                                                                            3.9   4  "        (5.73)                                    101.1                                                                              (1.00)                                                                              KNO.sub.3                                                                            9.9   --.sup.10                                        42   233.2                                                                              (0.50)                                                                              Bi.sub.2 O.sub.3                                                                     13.3  2.sup.9                                                                              160.0                                                                              1-F   41.6  "    "                        80.0 (0.50)                                                                              Fe.sub.2 O.sub.3                                                                     13.3  5.5.sup.9                                                                        2.7.sup.6                                                                              (1.57)                                    56.0 (1.00)                                                                              CaO    26.5  1.5.sup.9                                             12.4 (0.20)                                                                              H.sub.3 BO.sub.3                                                                     5.3   3.5.sup.9                                        43   58.3 (0.125)                                                                             Bi.sub.2 O.sub.3                                                                     14.0  2.sup.9                                                                              40.0 1-F   44.0  "    "                        20.0 (0.125)                                                                             Fe.sub.2 O.sub.3                                                                     14.0  5.5.sup.9                                                                        "        (0.39)                                    14.0 (0.25)                                                                              CaO    28.0  1.5.sup.9                                        __________________________________________________________________________                                       METAL/OXYGEN COMPOSITION                      ALUMINA/METAL                   ATTRITION                                  EX-                                                                              OXIDE(S)   PREPARATIVE CONDITIONS                                                                             RATE.sup.3                                                                           SURFACE                             AM-                                                                              MEAN PARTICLE                                                                            TEMPERATURE,                                                                            °C./TIME, HOURS                                                                   WT. %/ AREA.sup.4                          PLE                                                                              SIZE RATIO DRYING    CALCINATION                                                                              HOUR   m.sup.2 /g                                                                           EMPIRICAL                    __________________________________________________________________________                                                     FORMULA.sup.5                 2 9.5          200/5.sup.7                                                                              1000/10.sup.7                                                                         0.21   0.15   Bi.sub.15 Ca.sub.5                                                            ZrO.sub.x (Al.sub.2                                                           O.sub.3).sub.16                3*                                                                             5.9        "         "          0.42   0.09   "                             4 7.2        "         "          0.36   0.08   "                             5 6.3        "         "          0.21   0.22   "                             6 6.5        "         "          0.30   0.16   "                             7 8.1        "         "          0.19   0.09   "                             8 5.3        "         "          0.23   0.15   "                             9 7.8        "         "          0.30   0.17   "                            10 9.8        "         "          0.23   0.09   "                            11              200/2.sup.8                                                                           (1)1000/1.sup.8                                                                          0.19   0.52   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.                                                                      2 O.sub.3).sub.13                                    (2)1000/9.sup.7                                         12*                                                                            7.4        "         "          0.50   1.97   "                            13 8.9        "         "          0.41   0.52   "                            14 7.9        "         "          0.39   0.30   "                            15 8.2        "         (1)1000/1.sup.8                                                                          0.30   0.40   "                                                    (2)1000/9.sup.7                                       16 10.1       "         "          0.16   0.16   "                            17 6.6        "         "          0.21   0.54   "                            18 9.7        "         "          0.13   0.35   "                            19 12.2       "         "          0.26   0.20   "                            20 13.5       "            1000/10.sup.8                                                                         0.75   3.15   Pb.sub.10 Sb.sub.3                                                            O.sub.x (Al.sub.2                                                             O.sub.3).sub.15              21 10.5       "         "          0.26   0.11   Bi.sub.3 NiO.sub.x                                                            (Al.sub.2 O.sub.3).sub.3                                                      1                            22 19.4       "         "          0.54   >5     CoLaO.sub.x (Al.sub.2                                                         O.sub.3)                     23 12.2       "         "          0.17   1.54   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 KO.sub.x                                                             (Al.sub.2 O.sub.3).sub.19    24 12.8         250/2.sup.8                                                                           "          0.80   1.48   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 MgO.sub.x                                                            (Al.sub.2 O.sub.3).sub.18    25 12.9       "         "          0.50   1.67   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 ZnO.sub.x                                                            (Al.sub.2 O.sub.3).sub.18    26 12.8       "         "          0.53   1.82   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 LiO.sub.x                                                            (Al.sub.2 O.sub.3).sub.18                                                     1                            27 12.1         200/2.sup.8                                                                             1000/2.sup.8                                                                           0.27   0.36   (PbO.sub. x).sub.3                                                            (Al.sub.2 O.sub.3).sub.4                                                      0                            28 11.2         250/2.sup.8                                                                              1000/10.sup.8                                                                         0.18   0.71   Pb.sub.5 BiO.sub.x                                                            (Al.sub.2 O.sub.3).sub.18                                                     .                            29 12.2         200/2.sup.8                                                                              1000/10.sup.8                                                                         0.13   0.46   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.7     30 "            150/2.sup.8                                                                           "          0.25   0.69   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.18    31 "            200/2.sup.8                                                                           "          0.70   2.3    Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.28    32 "            250/2.sup.8                                                                           "          0.32   0.54   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.12    33 "            200/2.sup.8                                                                              900/10.sup.8                                                                          0.10   0.69   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.18    34 "            250/2.sup.7                                                                              1000/10.sup.7                                                                         0.38   0.33   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.12    35 "            250/2.sup.8                                                                              1000/10.sup.8                                                                         0.37   0.26   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.12    36 "            250/2.sup.8                                                                              1000/10.sup.7                                                                         0.29   0.34   Pb.sub.10 Sb.sub.3                                                            Bi.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.12    37-A                                                                             9.7        (1)200/1.sup.7                                                                          (3) 850/5.sup.7                                                                          0.35   0.17   BiO.sub.x (Al.sub.2                                                           O.sub.3)                                   (2)450/1.sup.7                                                                          (6) 850/1.sup.7                                                     (4)200/1.sup.7                                                                          (7)1000/4.sup.7                                                     (5)450/1.sup.7                                                  37-B                                                                             "          "         "          0.32   0.22   "                            37-C                                                                             "          (1)200/1.sup.7                                                                            (3) 650/1.5.sup.7                                                                      0.30   0.15   "                                          (2)450/1.sup.7                                                                            (4) 450/1.5.sup.7                                                           (5) 900/4.sup.7                                       37-D                                                                             9.9        (1)200/1.sup.7                                                                          (3) 850/5.sup.7                                                                          0.63   0.20   BiO.sub.x (Al.sub.2                                                           O.sub.3).sub.0.93                          (2)450/1.sup.7                                                                          (6) 850/1.sup.7                                                     (4)200/1.sup.7                                                                          (7)1000/4.sup.7                                                     (5)450/1.sup.7                                                  37-E                                                                             "          "         "          0.22   0.20   BiO.sub.x (Al.sub.2                                                           O.sub.3).sub.1.15            37-F                                                                             "          "         "          0.29   0.15   BiO.sub.x (Al.sub.2                                                           O.sub.3).sub.0.97            38-A                                                                             "          (1)500/1.sup.7                                                                          (2) 759/1.sup.7                                                                          0.20   0.20   Bi.sub.15 K.sub.5                                                             ZrO.sub.x (Al.sub.2                                                           O.sub.3).sub.16                                      (3)1000/9.sup.7                                       38-B                                                                             "          (1)200/5.sup.7                                                                           (3)1000/10.sup.7                                                                        0.16   "      "                                          (2)500/1.sup.7                                                  38-C                                                                             "          (1)200/2.sup.7                                                                            (3) 750/0.5.sup.7                                                                      0.38   0.12   "                                          (2)450/1.sup.7                                                                           (4)1000/10.sup.7                                     39 8.1        (1)200/5.sup.7                                                                           (3)1000/10.sup.7                                                                        0.25   0.35   Bi.sub.15 Ca.sub.5                                                            ZrO.sub.x (Al.sub.2                                                           O.sub.3).sub.16                            (2)450/1.sup.7                                                  40 7.9           970.sup.7                                                                              970/10.sup.7                                                                           0.19   0.22   Bi.sub.15 K.sub.4                                                             ZrO.sub.x (Al.sub.2                                                           O.sub.3).sub.16              41 7.6          200/5.sup.7                                                                              1000/10.sup.7                                                                         0.10   0.25   Bi.sub.30 K.sub.5                                                             Zr.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.29    42 28.5       (1)150/1.sup.7                                                                          (3) 750/1.sup.7                                                                          0.23   0.21   Bi.sub.5 Fe.sub.5                                                             Ca.sub.5 BO.sub.x                                                             (Al.sub.2 O.sub.3).sub.8     43 28.5       (1)150/1.sup.7                                                                          (3) 750/1.sup.7                                                                          0.33   0.18   Bi.sub.2 Fe.sub.2                                                             Ca.sub.2 O.sub.x                                                              (Al.sub.2 O.sub.3).sub.3                   (2)450/1.sup.7                                                                           (4) 950/16.sup.7                                     __________________________________________________________________________     .sup.1 Alumina Sample No. from Table 1.                                       .sup.2 Measured according to the manufacturer's procedure using a Leeds &     Northrup Microtrak instrument unless specified otherwise.                     .sup.3 Determined by the accelerated attrition test as described in           Example 44.                                                                   .sup.4 Measured according to ASTM D 366378 for surface area of catalysts      using a Micromeritics Digisorb 2500 instrument.                               .sup.5 The empirical formula, for convenience only, is written showing        alumina units associated with the remaining components. The alumina,          however, is an integral component of the infusion and reaction product.       Subscript "x" is a number taken to satisfy the average valences of the        metal elements (excluding aluminum) in the oxidation states in which they     exist in the compositions.                                                    .sup.6 Calculated weight average.                                             .sup.7 Air atmosphere.                                                        .sup.8 Nitrogen atmosphere.                                                   .sup.9 Measured by viewing on a calibrated grid using a microscope.           .sup.10 Dissolved and used as a solution.                                     .sup.11 Sample contained 20.8 weight % water.                                 .sup.12 Slow heat up at the rate of 2° C./minute.                      *Comparative example using an alumina outside the scope of the present        invention.                                                               

EXAMPLE 45

A. Toluene Converstion Reactor--A fluidized bed reactor was employedunless otherwise noted, in which case a fixed bed reactor was employed.

(1) Fluidized Bed--A stainless steel tube 38.1 centimeters (15 inches)in length and 1.27 centimeters (0.5 inch) outside diameter was employedas a fluidized bed reactor for the toluene conversion reaction. The tubewas capped on the bottom by a conical section that had a 30° angle. Thereactor was arranged vertically and equipped at the lower end withreactant inlet means for introducing the feed materials. The inlet meanswas fitted with a porous metal frit for gas dispersion. The reactor wasequipped at the upper end with reaction effluent outlet means fittedwith a 90 μm filter, for collecting the effluent or, alternatively, fordirect introduction thereof via a gas sampling valve into a gas-liquidchromatograph for analysis. A radiant furnace divided into twocompartments, an upper compartment and a lower compartment, was used asa heat source throughout the reaction period. The lower compartmentmaintained a constant temperature in the reaction zone while the uppercompartment maintained a lower, albeit constant, temperature(approximately 450° C.) in the gas expansion zone. The temperature wasmeasured with a thermocouple in a temperature well positioned inside thelength of the reactor.

(2) Fixed Bed--A stainless steel tube 20.32 centimeters (8 inches) inlength and 0.95 centimeter (0.375 inch) in internal diameter having ausable capacity of 11 milliliters was employed as a fixed bed reactorfor the toluene conversion reaction. The reactor was arranged verticallyand equipped at the upper end with reactant inlet means havingcalibrated flow controllers and vaporizers, and at the lower end withreaction effluent outlet means for collecting the reaction effluent or,alternatively, for direct introduction thereof via a gas sampling valveinto a gas-liquid chromatograph for analysis. The outlet means was alsoequipped with means for introducing an inert gas diluent--ntrogen orhelium, for example--into the reaction effluent for analysis purposes. Aradiant furnace was used to maintain a constant temperature during thereaction period. The temperature was measured with a thermocouple in atemperature well located on the lower outside wall of the reactor.

B. Toluene Conversion--The reaction was conducted in a stoichiometricmode of operation under fluidized conditions unless otherwise noted.

(1) Fluidized Bed--The reactor was charged with approximately 15milliliters of the attrition resistant metal/oxygen composition preparedas described in Examples 2-43, above. The reactor was placed in thetwo-compartment radiant furnace and heated to the operatingtemperatures, usually 575° C. for the reaction zone and 450° C. for thegas expansion zone, which temperatures were maintained throughout thereaction period. The reactor was operated at a pressure of 2.53×10⁵pascals (2.5 atmospheres, 36.7 psia) in a four-step cycle whichcomprised (a) passing a stream of air through the attrition resistantmetal/oxygen composition for a period of time ranging from 5 seconds to1 hour, usually 30 minutes (composition oxidation or regeneration); (b)purging the system with a 1/2 mole ratio feed mixture of nitrogen andwater for 1 minute (purge); (c) feeding a toluene/water mixture having a1/2 mole ration through the system for 3 minutes (toluenedehydrocoupling or composition reduction); and (d) purging the system asin step (b) (purge). The cycle was then repeated. The total molar feedrate during each step of the four-step cycle was maintained at 15-17millimoles/minute (about 557 cc/minute) flow rate which, under reactionconditions, provided a linear gas velocity of about 8.23centimeter/second (0.27 ft/sec) and a superficial reactor residence(contact) time of about 4 seconds unless specified otherwise. Samples ofthe reaction effluent were taken at 30-second intervals for analysis bygas-liquid chromatography. The results, integrated over the 3-minutedehydrocoupling step (c) period, are tabulated in Table 3.

(2) Fixed Bed--The reactor was charged with approximately 11 millilitersof the attrition resistant metal/oxygen composition prepared asdescribed in Examples 2-43, above. Glass wool plugs were used assupports for the composition. The charged reactor was placed in aradiant furnace and heated to maintain a constant temperature throughoutthe reaction period. Steam and toluene in a 2:1 mole ratio were fed tothe reactor at a pressure of 2.53×10⁵ pascals (2.5 atmospheres, 36.7psia) at a rate sufficient to provide a reactor residence (contact) timeof 3 seconds (unless otherwise noted) for the toluene (assuming a 50%void space in the reactor). After the reaction had proceeded for 1minute, the reaction effluent, diluted with helium, was analyzed bygas-liquid chromatography. The results are tabulated in Table 3.

                                      TABLE 3                                     __________________________________________________________________________               TEMPERATURE, °C./-                                                     SUPERFICIAL                                                        METAL/OXYGEN                                                                             CONTACT TIME,              SELECTIVITY, MOLE %                     COMPOSITION NO.                                                                          SECONDS.sup.1                                                                              CONVERSION, MOLE %                                                                          TRANS-STILBENE                                                                           COUPLING.sup.2                                                                       BENZENE               __________________________________________________________________________     2         --           --            --         --     --                     3         --           --            --         --     --                     4         --           --            --         --     --                     5         --           --            --         --     --                     6         --           --            --         --     --                     7         --           --            --         --     --                     8          560/2       11.0          52.0       82.0   13.0                   9            565/2.4   13.0          51.0       81.0   15.0                  10         --           --            --         --     --                    11         --           --            --         --     --                    12         --           --            --         --     --                    13         --           --            --         --     --                    14         --           --            --         --     --                    15         --           --            --         --     --                    16          520/2        8.0          56.0       74.0   16.0                  17          535/2        9.0          61.0       73.0   17.0                  18          550/2       19.0          69.0       83.0   14.0                  19         --           --            --         --     --                    20         560          41.0          74.0       79.0   11.0                  21         560          17.0          53.0       83.0    8.0                  22         560          10.0          43.0       62.0   21.0                  23         560          39.0          68.0       71.0   17.0                  24         560          44.0          74.0       75.0   14.0                  25         560          42.0          72.0       75.0   14.0                  26         560          41.0          74.0       78.0   11.0                  27         575          17.0          70.0       82.0   10.0                  28         560          25.0          68.0       78.0   12.0                  29         540          26.0          62.0       77.0   10.0                  30         570          35.0          62.0       67.0   14.0                  31         565          44.0          63.0       67.0   18.0                  32         560          32.0          65.0       71.0   17.0                  33         560          33.0          69.0       73.0   16.0                  34         560          48.0          75.0       79.0   12.0                  35         560          36.0          77.0       82.0    9.0                  36         560          37.0          77.0       85.0    8.0                  37-A        575/        11.0          47.7       81.2   11.9                                560/7.4   38.0          62.0       79.1   12.6                  37-B          535/0.6    5.2          48.2       87.2    5.6                  37-C          570/0.6    6.7          45.8       79.6    8.1                  37-D          565/0.6    7.7          50.4       79.4   11.9                  37-E          590/1.2    7.6          34.6       78.6   15.5                  37-F          575/1.2   13.5          53.9       87.1    7.9                  38-A          575/1.5   30.0          50.0       76.7   13.0                  38-B       540          30.0          62.0       83.0   10.0                  38-C        570/2       36.0          58.0       77.1   13.0                  39          565/2       40.0          62.0       76.0   16.0                  40          540/2       23.0          70.0       79.0   16.0                  41            550/2.5   26.0          57.0       67.0   18.0                   42.sup.3   580/3       22.0          61.0       82.0   18.0                   43.sup.3   580/3       25.0          59.0       77.0   21.0                  __________________________________________________________________________     .sup.1 A superficial contact time of about 4 seconds was employed in the      fluidized bed toluene conversion runs unless specified otherwise.             .sup.2 Selectivity to transstilbene + (cis stilbene + bibenzyl).              .sup.3 Fixed bed reactor was employed.                                   

EXAMPLE 46

This procedure illustrates a method of separating the stilbene in pureform.

Collect product streams from a number of toluene dehydrocouplingreactions in dry ice chilled traps. Flash distill the combined streamsto a 200° C. bottoms temperature and then batch distill through a2.5-centimeter inside diameter×90.0-centimeter long column packed withextruded metal. Collect the fraction having a boiling point at about186° C./20 mm mercury as transtilbene. The stilbene product is a white,crystalline solid having a melting point of 124°-125° C. and a retentiontime identical with an authentic sample of transstilbene as determinedby gas chromatographic coinjection.

Molten trans-stilbene reacts rapidly with atmospheric oxygen to formnumerous oxygenated (or polar) impurities, a major constituent of whichis benzophenone. As a result, molten trans-stilbene should be protectedfrom exposure to the atmosphere. Trans-stilbene so contaminated can bepurified by recrystallization from 95% ethanol to yield pure product.

Thus, it is apparent that there has been provided, in accordance withthe present invention, attrition resistant metal/oxygen compositions, aprocess for preparing same, and a process for utilizing suchcompositions to transform organic compounds, for example, todehydrocouple toluene to yield toluene dehydrocoupled products, thatfully satisfy the objects and advantages set forth hereinabove. Whilethe invention has been described with respect to various specificexamples and embodiments thereof, it is understood that the invention isnot limited thereto and that many alternatives, modifications, andvariations will be apparent to those skilled in the art in light of theforegoing description. Accordingly, it is intended to embrace all suchalternatives, modifications, and variations as fall within the spiritand broad scope of the invention.

What is claimed is:
 1. An attrition resistant metal/oxygen compositionwhich comprises the infusion and reaction product of:(a) 35 to 80 molepercent of an alumina existing in a crystal form selected from the groupconsisting of γ, δ, η, and χ crystal forms, and mixtures thereof, orthat can be transformed by heat to such crystal forms, and characterizedby(i) a mean particle size from about 10 μm to about 200 μm, (ii) afractional porosity of at least 0.2, (iii) a surface area of at least150 m² /g, and (iv) a pore diameter such that at least 10 percent of thepores are less than 55 A, and (b) 20 to 65 mole percent of at least onemetal oxide, or compound convertible by heat to such metal oxide, havinga maximum mean particle size of about 100 μm, with the proviso that thealumina/metal oxide mean particle size ratio is at least 2, which metaloxide is susceptible of undergoing infusion and reaction with thealumina upon being subjected to temperatures of at least 0.4 T_(m) for atime sufficient to cause infusion and reaction between the metal oxideand the alumina, wherein T_(m) is the melting point in °K. of thealumina wherein the composition is represented by the empirical formulaselected from the group consisting of Pb₁₀ Sb₃ Bi₂ O_(x) (Al₂ O₃)₇₋₂₈,Bi₁₅₋₃₀ K₄₋₅ Zr₁₋₂ O_(x) (Al₂ O₃)₁₆₋₂₉, (PbO_(x))₃ (Al₂ O₃)₄, Pb₅BiO_(x) (Al₂ O₃)₁₈, Pb₁₀ Sb₃ Bi₂ KO_(x) (Al₂ O₃)₁₉, Bi₁₅ Ca₅ ZrO_(x)(Al₂ O₃)₁₆, Bi₅ Fe₅ Ca₅ BO_(x) (Al₂ O₃)₈, and Bi₂ Fe₂ Ca₂ O_(x) (Al₂O₃)₃.
 2. The composition of claim 1 wherein the mean particle size ofthe alumina is from about 20 μm to about 125 μm.
 3. The composition ofclaim 1 wherein the alumina has a fractional porosity from about 0.2 toabout 0.8.
 4. The composition of claim 1 wherein the alumina particlesare spheroidal.
 5. The composition of claim 1 wherein the alumina is ahydrated alumina selected from the group consisting of Boehmite,pseudo-Boehmite, Bayerite, and Gibbsite.
 6. The composition of claim 1wherein the alumina/metal oxide mean particle size ratio is 15 or more.7. The composition of claim 1 wherein the metal oxide componentconcentration is in an amount from about 30 mole percent to about 55mole percent.
 8. The composition of claim 1 wherein the composition isrepresented by the empirical formula

    Pb.sub.10 Sb.sub.3 Bi.sub.2 O.sub.x (Al.sub.2 O.sub.3).sub.7-28

wherein x is a number taken to satisfy the average valences of Pb, Sb,and Bi in the oxidation states in which they exist in the composition.9. The composition of claim 1 wherein the composition is represented bythe empirical formula

    (PbO.sub.x).sub.3 (Al.sub.2 O.sub.3).sub.4

wherein x is a number taken to satisfy the average valence of Pb in theoxidation state in which it exists in the composition.
 10. Thecomposition of claim 1 wherein the composition is represented by theempirical formula

    Pb.sub.5 BiO.sub.x (Al.sub.2 O.sub.3).sub.18

wherein x is a number taken to satisfy the average valence of Pb and Biin the oxidation state in which they exist in the composition.
 11. Thecomposition of claim 1 wherein the composition is represented by theempirical formula

    Pb.sub.10 Sb.sub.3 Bi.sub.2 KO.sub.x (Al.sub.2 O.sub.3).sub.19

wherein x is a number taken to satisfy the average valences of Pb, Sb,Bi, and K in the oxidation states in which they exist in thecomposition.
 12. The composition of claim 1 wherein the composition isrepresented by the empirical formula

    Bi.sub.15-30 K.sub.4-5 Zr.sub.1-2 O.sub.x (Al.sub.2 O.sub.3).sub.16-29

wherein x is a number taken to satisfy the average valences of Bi, K,and Zr in the oxidation states in which they exist in the composition.13. The composition of claim 1 wherein the composition is represented bythe empirical formula

    Bi.sub.15 Ca.sub.5 ZrO.sub.x (Al.sub.2 O.sub.3).sub.16

wherein x is a number taken to satisfy the average valences of Bi, Ca,and Zr in the oxidation states in which they exist in the composition.14. The composition of claim 1 wherein the composition is represented bythe empirical formula

    Bi.sub.5 Fe.sub.5 Ca.sub.5 BO.sub.x (Al.sub.2 O.sub.3).sub.8

wherein x is a number taken to satisfy the average valences of Bi, Fe,Ca, and B in the oxidation states in which they exist in thecomposition.
 15. The composition of claim 1 wherein the composition isrepresented by the empirical formula

    Bi.sub.2 Fe.sub.2 Ca.sub.2 O.sub.x (Al.sub.2 O.sub.3).sub.3

wherein x is a number taken to satisfy the average valences of Bi, Fe,and Ca in the oxidation states in which they exist in the composition.16. The composition of claim 1 wherein the composition exhibits anattrition rate less than 0.5 weight percent/hour.
 17. The composition ofclaim 1 wherein the composition exhibits a surface area less than 5 m²/g.
 18. A process for the preparation of an attrition resistantmetal/oxygen composition which comprises:(a) forming a mixture of 35 to80 mole percent of an alumina existing in a crystal form selected fromthe group consisting of γ, δ, η, and χ crystal forms, and mixturesthereof, or that can be transformed by heat to such crystal forms, andcharacterized by(i) a mean particle size from about 10 μm to about 200μm, (ii) a fractional porosity of at least 0.2, (iii) a surface area ofat least 150 m² /g, and (iv) a pore diameter such that at least 10percent of the pores are less than 55 A,and 20 to 65 mole percent of atleast one metal oxide, or compound convertible by heat to such metaloxide, having a maximum mean particle size of about 100 μm, with theproviso that the alumina/metal oxide mean particle size ratio is atleast 2, which metal oxide is susceptible of undergoing infusion andreaction with the alumina and (b) heating the mixture to a temperatureof at least 0.4 T_(m) for a time sufficient to cause infusion andreaction between the metal oxide and the alumina, wherein T_(m) is themelting point in °_(K) of the alumina, and (c) recovering a compositionrepresented by the empirical formula selected from the group consistingof Pb₁₀ Sb₃ Bi₂ O_(x) (Al₂ O₃)₇₋₂₈, Bi₁₅₋₃₀ K₄₋₅ Zr₁₋₂ O_(x) (Al₂O₃)₁₆₋₂₉, (PbO_(x))₃ (Al₂ O₃)₄, Pb₅ BiO_(x) (Al₂ O₃)₁₈, Pb₁₀ Sb₃ Bi₂KO_(x) (Al₂ O₃)₁₉, Bi₁₅ Ca₅ ZrO_(x) (Al₂ O₃)₁₆, Bi₅ Fe₅ Ca₅ BO_(x) (Al₂O₃)₈, and Bi₂ Fe₂ Ca₂ O_(x) (Al₂ O₃)₃.
 19. The process of claim 18wherein the mean particle size of the alumina is from about 20 μm toabout 125 μm.
 20. The process of claim 18 wherein the alumina has afractional porosity from about 0.2 to about 0.8.
 21. The process ofclaim 18 wherein the alumina particles are spheroidal.
 22. The processof claim 18 wherein the alumina is a hydrated alumina selected from thegroup consisting of Boehmite, pseudo-Boehmite, Bayerite, and Gibbsite.23. The process of claim 18 wherein the alumina/metal oxide meanparticle size ratio is 15 or more.
 24. The process of claim 18 whereinthe metal oxide component concentration is in an amount from about 30mole percent to about 55 mole percent.
 25. The process of claim 18wherein the composition is represented by the empirical formula

    Pb.sub.10 Sb.sub.3 Bi.sub.2 O.sub.x (Al.sub.2 O.sub.3).sub.7-28

wherein x is a number taken to satisfy the average valences of Pb, Sb,and Bi in the oxidation states in which they exist in the composition.26. The process of claim 18 wherein the composition is represented bythe empirical formula

    (PbO.sub.x).sub.3 (Al.sub.2 O.sub.3).sub.4

wherein x is a number taken to satisfy the average valence of Pb in theoxidation state in which it exists in the composition.
 27. The processof claim 18 wherein the composition is represented by the empiricalformula

    Pb.sub.5 BiO.sub.x (Al.sub.2 O.sub.3).sub.18

wherein x is a number taken to satisfy the average valences of Pb and Biin the oxidation states in which they exist in the composition.
 28. Theprocess of claim 18 wherein the composition is represented by theempirical formula

    Pb.sub.10 Sb.sub.3 Bi.sub.2 KO.sub.x (Al.sub.2 O.sub.3).sub.19

wherein x is a number taken to satisfy the average valences of Pb, Sb,Bi, and K in the oxidation states in which they exist in thecomposition.
 29. The process of claim 18 wherein the composition isrepresented by the empirical formula

    Bi.sub.15-30 K.sub.4-5 Zr.sub.1-2 O.sub.x (Al.sub.2 O.sub.3).sub.16-29

wherein x is a number taken to satisfy the average valences of Bi, K,and Zr in the oxidation states in which they exist in the composition.30. The process of claim 18 wherein the composition is represented bythe empirical formula

    Bi.sub.15 Ca.sub.5 ZrO.sub.x (Al.sub.2 O.sub.3).sub.16

wherein x is a number taken to satisfy the average valences of Bi, Ca,and Zr in the oxidation states in which they exist in the composition.31. The process of claim 18 wherein the composition is represented bythe empirical formula

    Bi.sub.5 Fe.sub.5 Ca.sub.5 BO.sub.x (Al.sub.2 O.sub.3).sub.8

wherein x is a number taken to satisfy the average valences of Bi, Fe,Ca, and B in the oxidation states in which they exist in thecomposition.
 32. The process of claim 18 wherein the composition isrepresented by the empirical formula

    Bi.sub.2 Fe.sub.2 Ca.sub.2 O.sub.x (Al.sub.2 O.sub.3).sub.3

wherein x is a number taken to satisfy the average valences of Bi, Fe,and Ca in the oxidation states in which they exist in the composition.33. The process of claim 18 wherein the alumina and the metal oxide aredry mixed.
 34. The process of claim 18 wherein the alumina and the metaloxide are mixed by slurrying in a suitable wetting agent.
 35. Theprocess of claim 34 wherein the wetting agent is water.
 36. The processof claim 34 wherein the wetting agent is an organic compound selectedfrom the group consisting of methanol and ethanol.
 37. The process ofclaim 34 wherein the wetting agent is removed from the slurried mixtureof alumina and metal oxide by heating the mixture at a temperature ofabout 150° C. to about 250° C. for about 1 hour to about 5 hours. 38.The process of claim 18 wherein the mixture of alumina and metal oxideis heated to a temperature from about 0.47 T_(m) to about 0.74 T_(m) fora time from about 1 hour to about 15 hours.
 39. The process of claim 38wherein 0.47 T_(m) is about 800° C. and 0.74 T_(m) is about 1400° C. 40.The process of claim 18 wherein the composition exhibits an attritionrate less than 0.5 weight percent/hour.
 41. The process of claim 18wherein the composition exhibits a surface area less than 5 m² /g.